Screen tube



FIG. 1 is a perspective view of the screen tube;

FIG. 2 is an end view of the screen tube,

FIG. 3 is another end view opposite the view of FIG. 2 of the screen tube; and,

FIG. 4 is a side plan view of the screen tube; with views at 90°, 180° and 270° rotation being identical hereto.

The broken line showing of the tube is included for the purpose of illustrating boundaries and forms no part of the claimed design.

The depth of the interior surface shown in FIG. 3 forms no part of the claimed design. 

I claim, the ornamental design for a screen tube, as shown and described. 